Risk of disease outbreaks from ratoon rice

(Baonghean)Over the years, although the agricultural sector has advised farmers against cultivating ratoon rice (also known as seed rice) because it easily degrades the soil and reduces the quality and yield of rice at harvest; in the southern communes of Nam Dan district, the area of ​​seed rice from the spring crop is still over 300 hectares...

Mr. Phan Tam, residing in Hamlet 4, Nam Phuc Commune, planted 1.1 sao (approximately 1,200 square meters) of rice in the spring of 2012, achieving a yield of nearly 65 quintals per hectare. After harvesting, Mr. Tam did not prepare the land for the summer-autumn crop but left the old rice stubble, taking advantage of the time between the two crops to continue harvesting the ratoons. "In the spring crop, I planned to nurture the ratoons by planting X23 rice, because this variety has strong stubble and strong regenerative capacity. A few days before harvesting, I applied 7 kg of nitrogen fertilizer to increase the regenerative capacity of the stubble; at the same time, I continued to keep the field watered and controlled pests and diseases. After 50 days, I harvested twice (the first time was the ratoon rice, the second time was the rice flowering at the leaf axils), resulting in a yield of over 90 kg per sao," Mr. Tam said.

Nam Phuc commune (Nam Dan district) leaves 120 hectares uncultivated for the summer-autumn crop.
and nurture the rice seedlings.

In the Cau Bau rice field, Nam Trung commune, Mr. Nguyen Dinh Duc (from hamlet 9) after harvesting the spring rice crop, also proceeded to fertilize the old roots to nurture the new shoots on 1 sao (approximately 1000 square meters) of rice, yielding 1 quintal/sao. According to Mr. Duc, to nurture the new rice for high yields, when the rice is about 80% ripe, harvest it deeply, leaving about 20cm of the stubble. After about 10 days, the rice will continue to tiller. If you intend to nurture new rice, you need to choose the right variety at the beginning of the season; these are long-duration varieties with strong regenerative capacity, large clumps, fast flowering, and a low percentage of empty grains, such as X21, X23, BTE1... The advantage of new rice is that it doesn't require much land preparation, saves on seeds and fertilizer, the field has fewer weeds, the rice stalks are strong, and it is drought-resistant. After deducting investment costs, the yield of new rice reaches 1 quintal/sao.

The low-lying rice paddies in Nam Trung commune, such as the Rao, Chua Hoi, Cau Chay, and Trang Nam areas, currently have over 100 hectares producing two rice crops per year. However, this year, more than 30 hectares were not planted with summer-autumn rice; after the spring crop, farmers cleared the rice stubble to nurture the ratoons. According to Mr. Pham Van Phuong, Head of the Agriculture Committee of Nam Trung commune: "Previously, most of the ratoon rice paddies were not invested in or cared for, but were only used to feed ducks or buffaloes and cows... But after monitoring many seasons, farmers discovered that the ratoons from the previous crop continued to sprout vigorously and produce beautiful flowers. In 2011 alone, some households that cared for the ratoons achieved yields of 90-100 kg of rice per sao (approximately 1000 square meters). The ratoon rice has a short growing season, only 50-55 days, eliminating the need for rushed land preparation and avoiding early summer floods."

Mr. Thai Dinh Phu, chairman of the Nam Phuc Cooperative, said: Nam Phuc is a commune located in a low-lying area, and the annual summer-autumn crop often falls short of the planned target. According to the 2012 plan, the commune was supposed to plant 170 hectares of summer-autumn rice, but during the mobilization process, only 55 hectares were planted, mainly in the two high-lying areas of Xuan My and Dong Giong; in addition, farmers left 120 hectares for ratooning (an increase of 75 hectares compared to 2011). Of the 120 hectares of ratooning, only about 70 hectares are in the low-lying, swampy areas, making it less reliable for cultivation; the remaining more than 50 hectares in the high-lying areas could be cultivated, but this year, due to increased investment costs (currently, planting and harvesting costs 200,000 VND/sao, and land preparation costs 130,000-150,000 VND/sao), many people abandoned their fields and were not interested in planting the summer-autumn crop. This farming method is only a temporary solution for low-lying areas at high risk of flooding. While it may seem economically beneficial to households in the short term, the total income is very low. In Nam Phuc commune alone, to cultivate 120 hectares of rice seedlings to achieve an average yield of 1 quintal/sao (1 sao = 360 square meters), the total rice production would be 2,400 tons. If cultivated during the summer-autumn season, based on the average yield of 2.5 quintals/sao in previous years, the total food production would be 6,000 tons of rice.

In the 2012 summer-autumn crop season, Nam Dan district planned to cultivate 6,300 hectares of rice, but only achieved 5,900 hectares. Besides the abandoned area, the entire district still has nearly 300 hectares of rice seedlings, mainly concentrated in communes outside the dike, such as Nam Kim (85 ha), Nam Phuc (115 ha), Nam Trung (34 ha)... Mr. Nguyen Huu Nhuan - Head of the District Agriculture Department, said: "Ledgery cultivation is a farming practice that the district has advised people against, because the immediate benefits are low while the long-term consequences are dangerous. Rice seedlings provide a breeding ground for viral diseases, especially given the complex situation of rice yellow dwarf and rice leaf curl diseases. Furthermore, rice seedlings remain in the field for a long period (more than 3 months in the previous season and nearly 2 months in the current season), giving brown planthoppers more opportunities to transmit viruses than transplanted rice plants." Therefore, after harvesting the spring rice crop, if farmers leave the rice stubble behind, they inadvertently create a breeding ground for pathogens to reside and harm the next crop...

Ngoc Anh